1. Field of the Invention
Micellar combinations of cationic or anionic polymers and oppositely charged surfactants are made preferably with C6-23 alcohols in proportions coordinated in aqueous media with the aid of Zeta Potential measurements. The resulting gels are useful in drilling and formation fracturing in hydrocarbon recovery, manifesting excellent proppant suspending properties in low concentrations of polymer and surfactant as compared to the prior art.
In particularly, micellar combinations of cationic or anionic polymers and oppositely charged surfactants and further including an effective amount of a phosphorus-containing compound to sufficient to improve gel formation and stability are made preferably with C6-23 alcohols in proportions coordinated in aqueous media with the aid of Zeta Potential measurements and a phosphorus-containing compounds such as mono, di or tri carbyl phosphates or phosphate salts, which enhances gel viscosity, improved viscosity build up and improved viscoelastic properties such as stability.
2. Description of the Related Art
In U.S. Pat. No. 5,169,441, Lauzon suggests the use of Zeta Potential for characterizing particulates such as pigments treated with cationic polymers. Lauzon's U.S. Pat. No. 5,846,308 describes the stabilization of a rosin dispersion for use as a sizing composition by treating it with a “cationic colloidal coacervate” which may include both a cationic polymer and an anionic surfactant; the finished sizing composition is to have a Zeta Potential of at least 20 millivolts. Poly(diallyldimethyl ammonium chloride), sometimes known as polyDADMAC, is the preferred cationic polymer. Also, Lauzon's U.S. Pat. No. 6,315,824 describes a similar coacervate stabilizing system used for hydrophobic non-rosin sizing agents, which may be liquid as well as solid. See also Lauzon's U.S. Pat. No. 4,507,210, which suggests a correlation of Zeta Potential to certain filtration properties in the treatment of shale and clay in hydrocarbon recovery; see also Engelmann et al in U.S. Pat. No. 5,196,401.
Other compositions comprising a cationic polymer and an anionic surfactant, often in high ratios of anionic surfactant to cationic polymer, may be found in Matz and LeMar U.S. Pat. No. 6,110,451, Verdicchio and Spilatro U.S. Pat. No. 4,948,576, and the shampoo and other personal care products described by Guskey et al in U.S. Pat. Nos. 6,297,203 and 6,221,817, Sako et al in U.S. Pat. No. 6,284,230, (which also describes betaines) Hoshowski et al in U.S. Pat. No. 5,137,715, and Snyder et al in U.S. Pat. No. 6,248,317.
In the field of hydrocarbon recovery from the earth, formation fracturing fluids proposed by Zhang in Canadian patent 2,257,699 combine anionic surfactants such as sodium xylene sulfonate and cationic surfactants such as N,N,N,trimethyl-1-octadecammonium chloride to make a gel said to be viscoelastic. Carbon dioxide is added to similar combinations in Zhang's Canadian patent 2,257,697 to generate a foam. Borchardt et al, in U.S. Pat. No. 4,409,110, describe formation flooding compositions which may comprise cationic polymers and anionic surfactants. Numerous combinations of surfactants and other compounds are proposed by Dahayanake et al in U.S. Pat. No. 6,258,859 (WO 98/56497; PCT/US/12067). See also the compositions said to be viscoelastic and proposed for well treatment by Hughes et al in U.S. Pat. No. 6,232,274 and Jones et al in U.S. Pat. No. 6,194,356.
Combinations of cationic polymers, betaines, and anionic surfactants may be inferred from the numerous combinations of materials that are possibly 25 viscoelastic within the disclosure of Balzer in U.S. Pat. No. 5,956,502, dealing with compositions for use on the hair and skin. See also the combination of cationic polymer with anionic surfactants for use as an automatic dishwashing detergent, in Tartakovsky et al U.S. Pat. No. 6,281,180.
U.S. Pat. Nos. 7,205,262 and 7,183,239, which are also continuations-in-part of U.S. patent application Ser. No. 10/228,875, represent gellant system with other desirable properties, all incorporated herein by reference.
There remains a need for improved aqueous gels and methods of making them.